Mallacoota schellenbergi Ledoyer 1984

Lowry, J. K. & Hughes, L. E., 2009, Maeridae, the Elasmopus group *, Zootaxa 2260 (1), pp. 643-702 : 684-687

Mallacoota schellenbergi Ledoyer 1984

( Figs 23 , 24 )

? Maera insignis . — Schellenberg, 1938: 50, fig. 24.

Mallacoota schellenbergi Ledoyer, 1984: 69 , fig. 33. — Appadoo, Myers & Fagoonee, 2002: 776 , figs 6–9.

Mallacoota subcarinata . — Appadoo & Steele, 1998: 639.

Material examined. 1 male, 5.0 mm, 4 slides, AM P78038 ( JDT / OPH 3 b) ; 1 female, 4.2 mm, 1 slide, AM P78039 ( JDT / OPH 3 b) ; 1 male, 3 slides, AM P78040 ( JDT / OPH 3 b) ; 4 unsexed, AM P78041 ( JDT / OPH 3 b) ; 1 unsexed, AM P75623 ( QLD 1938 ) ; 8 unsexed, AM P75624 ( QLD 1942 ) ; 1 unsexed, AM P75625 ( QLD 1967 ) ; many unsexed, AM P75626 ( QLD 1988 ) .

Type locality. I’îlot Maître , New Caledonia (~ 22°20'0''S 166°24'0''E) .

Description. Based on 1 male, 5.0 mm, AM P78038.

Head. Head eyes ovate; lateral cephalic lobe broad, truncated, anteroventral margin with small ventral notch, anteroventral corner subquadrate. Antenna 1 longer than antenna 2; peduncular article 1 slightly longer than article 2, without robust setae along posterior margin; article 2 longer than article 3; accessory flagellum short, with 3 articles; flagellum with 16 articles. Antenna 2 peduncular article 4 longer than article 5; flagellum with 7 articles. Mandible incisor a smooth cutting edge with 2 apicomedial cusps; accessory setal row with 3 setae; palp reduced, 3-articulate; article 1 about twice as long as broad, shorter than article 2, inner margin article 1 not produced distally; article 2 shorter than article 3; article 3 long (more than 3 x as long as broad), rectolinear, article 3 longer than article 1.

Pereon. Gnathopod 1 coxa anteroventral corner produced, rounded, anterior margin concave; merus without posterodistal tooth; carpus about 2 x as long as broad, carpus shorter than propodus (length 0.7 x propodus), setae in anterodistal bunches and along posterior margin; propodus palm acute, straight, entire, defined by posterodistal corner, with posterodistal robust setae. Gnathopod 2 coxa posteroventral corner notch absent; basis slender; merus acutely produced distoventrally; carpus compressed, projecting between merus and propodus, length 0.73 x breadth; propodus expanded, witht setal bunches medially and along posterior margin, palm acute, smooth, with straight distomedial shelf, with group of 3 robust setae on shelf, palmar margin with 2 robust seta, without teeth along margin, with short proximal subpalmar seam forming rounded nodule, without posteroventral corner, without posterodistal robust setae; dactylus closing along palm, without setae on anterior margin, with posteroproximal shelf, apically subacute. Pereopod 4 coxa posteroventral lobe slightly developed, with subquadrate posteromedial corner. Pereopod 5 basis expanded, posterior margin convex, without long slender setae, posteroventral corner narrowly rounded; carpus and propodus with few long, slender setae along anterior margin. Pereopod 6 basis posterior margin convex, without long slender setae, posteroventral corner narrowly subquadrate; carpus and propodus with few long, slender setae along anterior margin; merus and carpus broadened; propodus not expanded posterodistally. Pereopod 7 basis posterior margin convex, smooth, without long slender setae, not produced posterodistally, posteroventral corner subquadrate; merus and carpus broadened; propodus not expanded posterodistally.

Pleon. Pleonites 1–3 dorsally smooth, without setae, spines or carinae. Epimeron 2 posteroventral corner acute. Epimeron 3 ventral margin smooth, posteroventral margin smooth, posteroventral corner with small acute tooth. Urosomite 1 bicarinate, subtriangular. Urosomites 2–3 dorsally smooth, without setae, spines or carinae. Uropod 1 peduncle with basofacial robust seta. Uropod 3 rami distally truncated, apical robust setae long; inner ramus shorter than outer ramus, short (length 1 to 1.9 x breadth); outer ramus short (length 1.8 x breadth), subequal in length to peduncle, 1-articulate. Telson deeply cleft (more than 66%), broader than long, tapering distally, apical margins concave, outer apical conical extension reaching scarcely one third along longest seta, without dorsal robust setae, each lobe with 3 long and 1 short apical robust setae, without robust setae on inner or outer margins.

Female (sexually dimorphic characters). Based on female, 4.2 mm, AM P78039. Gnathopod 2 carpus long, length 1.6 x breadth; without distomedial shelf, without robust setae along palm, with posterodistal robust setae; without posteroproximal shelf.

Habitat. Marine, epibenthic, intertidal algae.

Remarks. According to Ledoyer (1984) the material Schellenberg (1938) reported as Maera insignis may have been M. schellenbergi . Schellenberg had material from a wide range of localities in the Pacific Ocean including Hawaii, Fiji, Kiribati, Vanuatu and the Philippines. The material he illustrated and on which Ledoyer based his conclusion was from Kiribati.

Mallacoota schellenbergi is characterised by the male gnathopod 2 with dense rows of setae on the medial surface of the propodus, a lack of sculpturing on the palm, large, subpalmar nodules, and no posterodistal corner defining the palm. In most of these characteristics the propodus of male gnathopod 2 is similar to juvenile males of M. subcarinata ( Haswell, 1879b) (see Lowry & Springthorpe 2005).

On the GBR M. schellenbergi is distinct from other species of Mallacoota by the relatively unsculptured palm of male gnathopod 2.

Distribution. Australia. Queensland: Orpheus Island (current study), One Tree Island (current study). Kiribati. ( Schellenberg 1938). Mauritius. ( Appadoo & Steele 1998; Appadoo et al. 2002). New Caledonia. Southwest Lagoon ( Ledoyer 1984).

Figures

FIGURE 23. Mallacoota schellenbergi Ledoyer, 1984, male, 5.0 mm, AM P78038, Orpheus Island, Great Barrier Reef.

FIGURE 24. Mallacoota schellenbergi Ledoyer, 1984, male, 5.0 mm, AM P78038, female, 4.2 mm, AM P70839, Orpheus Island, Great Barrier Reef.